I'm converting it now to .imp and from there to .mobi/.prc and .epub, so thanks again for your (much appreciated) update to explode.c.

OK, I've completed the round one conversions of this to .mobi/.prc and .epub and the results were similar to my previous conversion to .imp.

Using Mobipocket Creator with standard compression resulted in a 138MB .prc whereas using calibre resulted in a 141MB .epub (see some sample ADE screenshots). In all three conversions, the images seem to be stored in full 16M color resolution (as extracted from explode.exe) and the culprit for the tremendous filesize increase. The (compressed) text occupied only about 10% (12 to 15MB) of the resulting ebooks.

Time to focus on image resolution reduction, but I may ( will! ) not probably get ANY better compression result than Plucker's 43MB .pdb, so this is an exercise in futility, but I don't mind...